The most common ways to remediate polycyclic aromatic hydrocarbon (PAH) contamination at Superfund sites include chemical oxidation, bioremediation and thermal treatment. All of these remediation strategies have the potential to form hazardous oxy- and hydroxy-PAH breakdown products by oxidizing parent PAH. However, the peer-reviewed literature contains few studies of the formation of these chemicals during PAH remediation, for at least three reasons: the inability to predict which oxy- and hydroxy-PAHs will form in complex environmental mixtures, the complexity of the chemical analysis of oxy- and hydroxy-PAHs, and the historical lack of oxy- and hydroxy-PAH standards. As a result, regulatory agencies and researchers monitor the degradation of parent PAH during remediation of Superfund sites, but not the formation of hazardous PAH breakdown products. We hypothesize that parent PAHs transform into more persistent, water soluble, bioavailable, and toxic PAH breakdown products during the remediation of PAH-contaminated Superfund sites. Our first specific aim is to predict and measure PAH breakdown products formed from the oxidation of parent PAHs on the basis of computational modeling, controlled laboratory experiments, and two-dimensional gas chromatography equipped with time-of-flight mass spectrometry (GCxGC/ToF-MS). Our second specific aim is to measure PAH breakdown products directly in soils and sediments from former wood treatment Superfund sites, pre- and post-remediation, by GCxGC/ToF-MS. Our third specific aim is to determine which PAH remediation technologies minimize the formation of hazardous PAH breakdown products and assess the potential risk. We plan to measure soil and sediment samples from pilot scale remediation testing and determine if the parent, oxy-, and hydroxy-PAH concentrations increase or decrease with testing. We will determine which remediation conditions and soil and sediment properties affect the formation of hazardous PAH breakdown products. We will also collaborate with the Research Translation Core to provide guidance to Superfund managers regarding the human risk assessment of hazardous PAH breakdown products and appropriate remediation strategies to minimize their formation.